Structure of the SARS-CoV nsp12 polymerase bound to nsp7 and nsp8 co-factorsRecent history is punctuated by the emergence of highly pathogenic coronaviruses such as SARS- and MERS-CoV into human circulation. Upon infecting host cells, coronaviruses assemble a multi-subunit RNA-synthesis complex of viral non-structural proteins (nsp) responsible for the replication and transcription of the viral genome. Here, we present the 3.1 Å resolution structure of the SARS-CoV nsp12 polymerase bound to its essential co-factors, nsp7 and nsp8, using single particle cryo-electron microscopy. nsp12 possesses an architecture common to all viral polymerases as well as a large N-terminal extension containing a kinase-like fold and is bound by two nsp8 co-factors. This structure illuminates the assembly of the coronavirus core RNA-synthesis machinery, provides key insights into nsp12 polymerase catalysis and fidelity and acts as a template for the design of novel antiviral therapeutics.
Assembly of the Ebola Virus Nucleoprotein from a Chaperoned VP35 ComplexEbolavirus NP oligomerizes into helical filaments found at the core of the virion, encapsidates the viral RNA genome, and serves as a scaffold for additional viral proteins within the viral nucleocapsid. We identified a portion of the phosphoprotein homolog VP35 that binds with high affinity to nascent NP and regulates NP assembly and viral genome binding. Removal of the VP35 peptide leads to NP self-assembly via its N-terminal oligomerization arm. NP oligomerization likely causes a conformational change between the NP N- and C-terminal domains, facilitating RNA binding. These functional data are complemented by crystal structures of the NP°-VP35 complex at 2.4 Å resolution. The interactions between NP and VP35 illuminated by these structures are conserved among filoviruses and provide key targets for therapeutic intervention.
A library of nucleotide analogues terminate RNA synthesis catalyzed by polymerases of coronaviruses that cause SARS and COVID-19Spike and nsp6 are key determinants of SARS-CoV-2 Omicron BA.1 attenuationStructure of the SARS-CoV NSP12 polymerase bound to NSP7 and NSP8 co-factorsRobert N. Kirchdoerfer, Andrew B. Ward|bioRxiv (Cold Spring Harbor Laboratory)|2019 Recent history is punctuated by the emergence of highly pathogenic coronaviruses such as SARS- and MERS-CoV into human circulation. Upon infecting host cells, coronaviruses assemble a multi-subunit RNA-synthesis complex of viral non-structural proteins (NSP) responsible for the replication and transcription of the viral genome. Here, we present the 3.1 Å resolution structure of the SARS-CoV NSP12 polymerase bound to its essential co-factors, NSP7 and NSP8, using single particle cryo-electron microscopy. NSP12 possesses an architecture common to all viral polymerases as well as a large N-terminal extension containing a kinase-like fold and is unexpectedly bound by two NSP8 co-factors. This structure illuminates the assembly of the coronavirus core RNA-synthesis machinery, provides key insights into NSP12 polymerase catalysis and fidelity and acts as a template for the design of novel antiviral therapeutics.